General Questions

How do I add turbines in Openwind?

First, right-click in the left-hand panel and choose New Layer. Then selectTurbine Layout from the next pop-up. This will add a Site Layer in the left panel. You can now add turbines by editing the layer and right-clicking in the map view to add a turbine. You can also add a turbine to the Site Layer by right-clicking and choosing Properties. Then move to the Turbine Coordinates tab using the Autoplace option or paste in turbine coordinates from a spreadsheet program.

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How do I edit a layer?

First select the layer you want to edit in the left-hand panel. Then click the toolbar button, which looks like an arrow and “s” shaped line. This is the edit button. Once you have completed this and are in edit mode (button will appear in the pressed position) you can move points by left-clicking and dragging, or you can insert new points by right-clicking. Press the Delete key to delete the last selected point.

When editing lines or polygons, hold down the Shift key while you right-click. This will start a new line or polygon. If you hold down the Ctrl key while right-clicking you will start a new sub-line or sub-polygon.

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How do I print in Openwind?

You can print the contents of the screen at any time by clicking File > Print to. Then choose the device or file format.

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How do I associate a met mast or wind frequency table with a Wind Resource Grid?

Whenever at Wind Resource Grid (WRG) requires information about the wind resource at a point, it checks to see if it has a wind frequency table associated with it. It does this by asking children and grandchildren layers for the wind frequency table information. If it finds a wind frequency table it will use it, but it will only use the first one it finds.

In order to associate a wind frequency table or met mast with a WRG you must make a wind frequency table a child or grandchild of the WRG. You can do this by dragging and dropping the met mast layer on the WRG layer.

Don’t forget to load a single point WRG by going into the met mast layer’s properties and selecting the Load Point WRG button.

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How do I limit turbines to specific areas?
How do I load a background image?

Click File > Open Image and browse to the image you want to use. Openwind can import images in common formats (TIF, BMP, JPG, and PNG). Once you load a TIF, Openwind will automatically look for a TIFW file and take the coordinates for the image. Otherwise, it will ask for the coordinates of the four edges of the image.

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How do I load Raster Data?

Openwind has the capability to make the distinction between images that are decorative (do not contain an obvious grid of data values) and rasters (grids of values). Openwind contains functions to convert images into rasters. However, if you want to import gridded data into Openwind, it is best to use one of the following file formats: ESRI, ASCII grid (*.ASC); Surfer ASCII grid (*.GRD); WindFarmer digital terrain model (*.DTM); ESRI floating point grid (*.ADF); Binary interleaved data (*.BIL); GeoTIFF (*.TIF): Idrisi grid (*.RST).

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How do I load a Wind Resource Grid?

Use File > Open Wind Resource Grid and browse to the WRG you want to load. At present we support WasP format WRG’s.

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How do I load a Wind Frequency Table?

Use File > Openwind Frequency Table and browse to the WasP TAB file you want to load. You will need to edit the properties of this layer to add the single point WRG. We refer to these layers interchangeably as “met masts” and “wind frequency tables.”

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What coordinate systems does Openwind support?

Openwind has a lot of GIS features, but there are some differences to note. The first is that Openwind does not project on the fly. The second is that Openwind only works in meter grids, as this is important to facilitate small-scale physical models. Openwind will convert from Geographic (lat/lon) coordinates to UTM coordinates when importing data. At present, Openwind only supports standard UTM zones. If you have all your data in another single, consistent meter grid projection you can use Openwind.

Once you specific a UTM zone then that is the zone that will be used for any future conversions. If you do not specify a UTM zone, Openwind will set it based on the first set of geographic coordinates it encounters. If you change the UTM zone within a workbook, Openwind will not re-project the data already in the workbook. Conversions are carried out once the data is imported. It is not projected on the fly.

Openwind supports WGS84 world datum at present although we may add others at users’ requests. Openwind is unlikely to ever support datum conversion, but you can do this using your GIS of choice.

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How do I know Openwind is giving me the right answers?
How do I export a layer?

Simply right-click on the layer you want to export and then select export. You will be prompted for a file name. You can select the file format to export to using the drop down list at the bottom of the Save File dialog. For example, in order to save a turbine layout to Google Earth you right click on your site layout, select export, and then choose Google Earth KML as the export type. The will create a Google Earth compatible KML file, which references turbine models on this server and can be used to create an animated simulation of a wind farm.

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Why are the dialogs so small?

Almost all the dialogs can be resized, so what you see by default is the minimum size of each dialog. Grab the bottom right corner and drag to get a bigger window.

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How does the optimizer work?

The optimizer checks whether the current layout is legal (i.e. that all turbines obey all the current constraints and have appropriate wind resource information). If this is not the case, it attempts to find random positions for the turbines. If this fails, it attempts to pack the turbines.

Once a legal layout is available, the optimizer does a full test of the layout to get the starting energy. Next it tests the layout again to get its first optimizing benchmark. Then it begins to optimize the layout.

Each iteration of the optimizer consists of the following steps:

  1. The optimizer attempts to find a new legal position for each turbine. If the turbine placement was good in the last iteration, it will attempt the same direction this time (this momentum allows turbines to climb hills more effectively). Otherwise, it finds a new random perturbation. It does this by adding a gaussianly distributed random perturbation to the turbines x and y coordinates. If the new position is not legal or it obstructs another turbine’s perturbed of fallback position, a random perturbation is made and so on until all the turbines have new legal positions.
  2. The optimizer will run an energy capture (which includes wake effects) and if the total energy is greater than the benchmark energy, it accepts the entire new layout (this happens at the beginning of the optimization process) and the perturbed positions become the permanent positions and the new energy the benchmark energy, the perturbation is discarded and the turbine is returned to its permanent position and benchmark energy.
  3. If the new layout was not accepted as a whole, the optimizer looks at each turbine in turn and if that turbine got less than its benchmark energy, the perturbation is discarded and the turbine is returned to its permanent position and benchmark energy.
  4. The optimizer them sums the total energy from all the turbines and if it is equal or greater than the benchmark energy, it runs another energy capture to see if it really constitutes an improvement. If not then we discard all the perturbations and return to step 1. If so, we accept all these new positions and energies as the benchmark energies and return to step 1.

Now you can go through steps 3 and 4 again (hence the third set of lines in red sometimes). Attempts are ongoing to address the weaknesses of this method.

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How do I make a wind map in Openwind?
  1. Right-click in the left-hand pane (the tree view) and choose New Layer then windmap
  2. Drop an elevation raster onto the windmap layer (make sure you have it marked as elevation in the raster properties).
  3. Drop on or more TAB files onto the windmap layer
  4. Drop a roughness raster onto the windmap if you have one
  5. Drop a vegetation height raster or polygon layer onto the windmap if you have one and want to use displacement heights.
  6. Right-click on the windmap layer and choose Calculate
  7. The cursor will change. After this use it to drag a box from top left to bottom right describing the area you want as your new windmap.
  8. Choose the parameters for your windmap including how many, and which output heights and press ok.
  9. Sit back and wait – Openwind will multi-thread the calculation.
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